Not only do fruits and vegetables contain plenty of vitamins, minerals and fibre, there is something else about fruits and vegetables that makes them special.
Fruits and vegetables contain phytochemicals (pronounced ‘fight-o-chemicals’). They are nature’s chemicals found in plant foods, responsible to a large degree for the protective properties of fruits and vegetables. In addition, it is the phytochemicals that give fruits and vegetables their distinctive colours and smells.
We generally classify fruits and vegetables into five colour groups according to the phytochemicals they contain - green, yellow/orange, red, blue/purple and white/brown. There are many different phytochemicals that work together to protect your health. You will probably find that some have quite unusual names but don’t let this deter you from finding out about their unique health benefits. To ensure you receive a great variety of phytochemicals in your diet, choose fruits and vegetables from each of the colour groups every day.
Red foods
The phytochemicals lycopene, ellagic acid and a flavonoid called kaempferol contribute to the special features of red fruit and vegetables. Red foods include:
| tomatoes | red capsicum | radishes |
| strawberries | rhubarb | cherries |
| red grapes | raspberries | red cabbage |
These phytochemicals act as antioxidants, can be cancer protective and can also help reduce the risk of heart disease. Lycopene is a powerful antioxidant belonging to the group of carotenoids. A high intake of lycopene in particular has been linked with a reduced risk of prostate cancer.
Purple/blue foods
The colour in purple/blue fruits and vegetables is mainly due to the flavonoids, such as anthocyanins, which are powerful antioxidants and have a mild anti-bacterial effect. Another phytochemical discovered in this group of fruits and vegetables includes resveratrol, which is most commonly found in grapes and may have a cancer protective effect. Purple/blue foods include:
| beetroot | purple asparagus | red cabbage |
| eggplant | blackberries | blueberries |
| purple grapes | plums | purple potatoes |
Brown/white foods
While these colours are not as vibrant as the other colour groups, we should not underestimate the nutritional contribution that brown/white fruit and vegetables can make to our diet. Brown/white foods include:
| cauliflower | garlic | ginger |
| mushrooms | onions | potatoes |
| bananas | brown pears | dates |
| white peaches | nectarines | parsnips |
Fruits and vegetables from this group contain phytochemicals including allicin, indoles and isothiocyanates, to name just a few. Many of the phytochemicals found in this group of foods have effects ranging from antibacterial, antiviral and anti-cancer, to the prevention of heart disease. This knowledge goes some way to understanding the long held belief that garlic is good for you!
Orange/yellow foods
There are abundant antioxidants in yellow and orange fruit and vegetables, including the carotenoids (beta-carotene, lutein, zeaxanthin), which give this group their bright colour. A wide range of other phytochemicals including terpenes and flavonoids (quercetin) also occur in this group. Orange/yellow foods include:
| carrots | pumpkin | corn |
| oranges | rockmelon | lemons |
| mangoes | pineapples | kumara |
Carotenoids, terpenes and flavonoids act as antioxidants to protect against cancer and heart disease. Of interest is lutein (pronounced ‘loo-teen’), which is a carotenoid that is stored in the eye. This is important to help prevent two of the most common causes of blindness: cataracts and age-related macular degeneration.
Green foods
Like orange/yellow foods, green fruits and vegetables are particularly rich in antioxidants. They include varying amounts of many phytochemicals including flavonoids and carotenoids (lutein, beta-carotene and zeaxanthin). The Brassica group (broccoli, cabbage, brussel sprouts) also contains indoles, which can trigger enzymes to act against certain cancer causing substances. Saponins, another phytochemical found in green plant foods, also have anti-cancer properties. They interfere with the process whereby cancer cells multiply. Green foods include:
| spinach | broccoli | asparagus |
| peas | avocados | green apples |
| green grapes | limes | kiwifruit |
| green pears | leafy greens cabbage |